Fighting air pollution in the Third Pole

Dr. Khushboo Sharma, an Air Pollution Analyst at the International Centre for Integrated Mountain Development (ICIMOD) in Kathmandu, reviews air pollution in the Hindu Kush Himalaya and analyses that it is a growing existential threat, impacting health, glaciers, and regional stability. The deadly PM2.5 and black carbon emissions accelerate climate impacts and glacial melt. Regional coordination, clean technologies, and public-private partnerships can protect this vital ecosystem.

Air pollution is an environmental concern and an existential threat to the human race, vital water resources, and regional stability. The Hindu Kush Himalaya (HKH) region is often referred to as the ‘Third Pole’ because it features the largest area of frozen water outside the polar regions. It sustains nearly 240 million mountain people and supports water and food security for over 1.6 billion people downstream. Yet this critical ecosystem faces growing threats from air pollution, especially particulate matter (PM2.5 and PM10) and black carbon (BC).

The State of Global Air 2024 report states air pollution is the second leading risk factor for death worldwide, linked to approximately 8.1 million deaths in 2021, including over 700,000 among children under five. A staggering 99% of the global population lives in areas where PM2.5 readings exceed WHO guidelines; South Asia is among the worst, where it is the leading health risk, causing an estimated 2.6 million deaths that year. In April 2025, PM2.5 levels in the Kathmandu Valley reached over 77 times the World Health Organisation’s safe limit, with residents experiencing unhealthy air on 75 out of the past 90 days, starkly highlighting the need for urgent, inclusive, and sustained clean air action across the Hindu Kush-Himalayan (HKH) region.

Multiple sources of pollution

Airborne pollutants in the HKH arise from multiple sources. Outdoor pollution originates from transportation emissions, open biomass burning (including crop residue, garbage, and forest fires), industrial emissions (such as brick kilns, steel and cement industries, boilers, and furnaces), and construction dust. Indoor air pollution, a still largely silent killer, results from the use of solid fuels such as wood, coal, and dung for cooking and heating. Poorly ventilated homes and reliance on traditional stoves expose millions, especially women and children, to hazardous pollutants. Among these, black carbon is particularly concerning, which is also a subset of PM2.5.

Impacts of BC

Black carbon (BC) is a fine particulate pollutant produced by the incomplete combustion of fossil fuels, biomass, and waste. Commonly seen as soot, it is a short-lived climate pollutant (SLCP) with a short lifespan but has devastating longer-term consequences. BC has a dual impact that degrades air quality and disrupts climate systems. When deposited on snow and ice, BC reduces surface albedo (reflectivity), accelerating the melting of glaciers and snowpacks. This absorption of heat causes local warming, especially in high-altitude HKH regions. It is alarming as glacial retreat threatens long-term water availability for agriculture, hydropower, and domestic use. The warming potential of BC is up to 1,500 times greater than CO₂ per unit mass. A study by ICIMOD’s scientists on Nepal’s Yala Glacier found that BC accounts for up to 39 percent of glacial melt during the pre-monsoon period. Research from the Tibetan Plateau revealed that BC contributes to 20 percent of albedo reduction during the melt season. The Climate Action Framework (2025) reports that BC-induced warming and snow darkening have accelerated the retreat of Himalayan glaciers by 50 per cent, with cascading effects on the Indian monsoon. ICIMOD’s 2019 report, the HKH Climate Assessment, also flags BC as a key driver of short-term regional warming. Beyond accelerating glacier melt, BC heats the atmosphere and dims the surface, thus destabilising monsoon circulation. It disturbs rainfall and triggers floods and droughts, directly threatening food security in monsoon-dependent regions such as the HKH. BC emissions also disrupt South Asian and West African monsoons, leading to more extreme precipitation events that harm agriculture, livelihoods, and well-being while contributing to localised atmospheric warming and intensified heat extremes.

In the HKH region, over 60 per cent of rural households rely on biomass fuels, such as wood, dung, and crop residue, for cooking and heating, driven by energy poverty and cultural practices (World Bank, 2019). In addition to indoor air pollution from these sources, vehicle emissions, industrial activities, and the use of fossil fuels in homes and agriculture contribute significantly to overall air pollution levels and associated health risks in the HKH region. This situation is exacerbated by limited air pollution monitoring and weak regulatory enforcement across many countries in the HKH region. Seasonal factors, such as frequent forest fires during the dry season and crop residue burning during the pre-monsoon and winter seasons, further increase black carbon levels. Rapid urbanisation, industrialisation, and inefficient cooking and heating technologies sustain high emissions. Unplanned city growth, traffic congestion, and booming construction amplify pollution. However, industrial emissions, particularly from brick kilns and small-scale manufacturing facilities, persist due to inadequate enforcement and slow adoption of cleaner technologies.

Advancing a regional approach to tackling air pollution

ICIMOD plays a catalytic role in strengthening air quality monitoring and data analysis, raising public awareness and fostering regional collaboration on transboundary air pollution. Its initiatives include supporting the installation and expansion of Ambient Air Quality Monitoring Stations (AAQMS) across partner countries, as well as partnering with national and international institutions to measure emission factors from key sectors, including brick, cement, and steel. It also utilises advanced modelling tools, such as WRF-Chem and SHERPA/TM5-FASST, for chemical forecasting and to assess emission reduction strategies. ICIMOD also co-develops open-access dashboards and country status reports to support evidence-based planning, facilitates regional consultations, and has initiated efforts to advance harmonised air quality standards through ongoing Science Policy and Finance Dialogues. Beyond technical efforts, ICIMOD promotes cleaner technologies and supports brick kiln transitions to more efficient designs, such as zigzag kilns, which substantially reduce particulate emissions. The organisation encourages pelletisation as an alternative to open crop residue burning, a significant source of seasonal pollution. ICIMOD also advances cleaner residential heating and cooking solutions to reduce household air pollution and improve health outcomes, especially for women and children. Additionally, ICIMOD supports grassroots programs, such as Clean Air Champions, which link citizen science with policy engagement and collaborate closely with national environmental departments to integrate air quality into broader climate and health policies.

While some HKH cities are beginning to pilot real-time indoor air quality (IAQ) monitoring and draft guidelines, enforceable IAQ standards remain scarce. Data alone cannot drive change; sustained public awareness campaigns, education, and strategic media engagement are vital to shift behaviours. Empowering vulnerable communities with knowledge about the health risks of indoor pollution and their right to clean air is crucial for building grassroots momentum toward healthier indoor environments (UN Women, 2023). Governments in the HKH have made commendable strides in air quality regulations and implementation, with India leading the efforts and launching the “Compendium of Viable Technologies and Practices” during the September 7, 2024, Clean Air Day (Swachh Vayu Diwas) event under the National Clean Air Programme (NCAP). Yet greater private sector involvement is needed to sustain and accelerate progress. Strong public-private partnerships, innovative clean technologies, and responsible business practices can foster cleaner air and protect the fragile HKH ecosystem. By embedding environmental responsibility, the private sector can become a key partner in driving sustainable innovation through improved fuel efficiency and strict emission controls.

Tackling the PM and black carbon crisis requires a multisectoral approach and collective effort, including but not limited to –

·         monitoring, innovation, and awareness: leveraging emerging tools, from low-cost sensors to AI-driven forecasting models, to transform how we understand and act on air quality;

·         brick kiln modernisation: scaling up cleaner technologies like zigzag, tunnel and hybrid Hoffman’s kilns;

·         agricultural solutions: supporting crop residue management and pelletisation to reduce open burning;

·         sustainable urban planning: designing cities with green corridors, better public transport, and emission zoning;

·         health-aware regulation: linking air quality indices with hospital burden and early warning systems;

·         clean energy transitions: expanding access to LPG, electric cooking, and renewable alternatives to reduce household air pollution;  

·         regional cooperation: working in harmony to address cross-border air pollution issues, recognising that air pollution respects no boundaries and demands coordinated, transnational responses.

An existential threat

The time to act is now. The HKH faces intertwined challenges of climate change, public health, and rapid urbanisation, all linked by the urgent threat of air pollution. Fine particulate matter and black carbon are not just environmental concerns but existential risks to humankind, vital water resources, and regional stability. Protecting this critical region requires integrating science and policy by leveraging high-resolution emissions data and climate models for targeted air quality and climate actions. Prioritising the reduction of short-lived climate pollutants, such as black carbon, can deliver near-term climate and health benefits. Strengthening regional cooperation is essential, as air pollution knows no borders and demands coordinated cross-country efforts. Mitigating black carbon protects the cryosphere, slowing glacier melt and safeguarding water security for millions downstream.

Air pollution should never be an inevitable cost of development but a call to align growth with environmental and health priorities.

Expertise shared by–

Dr. Khushboo Sharma
Air Pollution Analyst
ICIMOD Kathmandu